1. Field of the Invention
The present invention relates to a novel camera tracking system for a virtual television or video studio.
2. Description of the Background Art
In producing virtual film or video sequences, the images recorded by a camera, for example, images of a person, are combined in a special device with a background (electronic set) that is not really present (i.e. virtual), or with other details generated in the device (a so-called virtual studio). In order to integrate the person filmed by the camera into the virtually generated background with precision and positional accuracy, the respective actual position and orientation of the recording camera (studio camera) must be known.
Conventionally, the position of the recording camera has been calculated, starting from a zero position, by measuring the distance traveled and the Orientation of the camera has been determined by measuring the pivot angle, the pitch angle, and the rolling angle using corresponding incremental sensors (Sommerhäuser, F.: Das virtuelle Studio; in: FERNSEH- UND KINO-TECHNIK, 50. Jhrg., 1996, Nr. 1-2, p. 11-15, 18-22). To this end it is necessary to install corresponding incremental sensors on the camera and at each joint and at each axis of its stand (tripod). This known system requires a relatively high effort in measurement techniques.
From Interner Broadcast Convention IBC '97, Convention Publication, pages 284-289, and WO-A-94105118, respectively, a camera tracking system is known wherein the camera is provided with an auxiliary camera directed towards the studio ceiling for detecting bar code marks on the studio ceiling. Using the bar codes detected by the camera, a corresponding computer can determine the exact position of the camera in the studio. Through this known camera tracking system, the position of the camera in the studio may be determined, however, incremental sensors still have to be used to determine the height of the camera above the ground and to determine the pivot angle, the rolling angle and the pitch angle of the camera.
From EP-A-0 689 356, a voice controlled video system is known, wherein a video camera is orientated by the voice of a person. Here, a person sends signals to the video system via corresponding emitters so that the video camera can follow the movements of the person in order to permanently detect the person.